alright, i did a quick volt meter test on the icp circuit to prove my point on the resistors, i had a hard time as it s dark and am by myself, the one picture the meter poped out of the connector and the pic didnt catch the meter in time. but here is the test overview.
Truck is at idle- first measurement (PIC 1) icp sensor output to pcm voltage was 1.2 volts, the pic didnt catch the meter in time, but i post this anyway to show where i measured. this is what the pcm would normally see as icp volts.

test number 2- truck is still at idle- volt probe after icp 10k resistor, notice the reading is now down to .966 volts. the resistor causes the siganl to use its voltage to overcome the resistor and get to the pcm, now the pcm will see the lower voltage and close the ipr to bring the oil pressure up to what it thinks is correct.

tomarrow after the wifey gets home i will do it again and be able to hold the leads while she takes the pictures, also i will do the same thing at wot and re-run each test with the 5k. 10k, and 22k to show that the more resistance you add the less voltage the pcm will see and raise the oil pressure accordingly. i hope this is enough to convince you guys for now untill i can get a sexy assistant....lol

 

So it would be better idea to buy a 50K potentiometer instead a 10K?

 

no definatly not at this point, i put the 22k in last nite and have som eissues with a flat line in power, i wanted to do testing on it tomarrow but it looks like i cant get the ford scanner i require ( my buddies wife had a baby last nite) until later on so the 22k may be on hold for a few days. i am bummed about that since the 1st gear power was mind boggling, the 10k is good, but i want to figure out the 22k and see if i have a pump problem or a defuel problem, either way 50 k will be way to much in my opinion at this point in time

 

That sounds like testing might take awhile,whatta wife you must have.Mine won't even hand me wrenches,but that's why I have growing teenage boy-to teach(gofer).Great kid though ..

 

Well, we will be waiting for more of your info. Thanks again.

 

Good explaination Joe, Your the first to explain why it works, electrically anyway. Capacitance sensor is what confused me I guess. MOre resistance should = more pressure if I read that right.....to a point. I tried to rep ya but I gotta spread the love 1st.

 

wow, joe. you did a great job explaining that to us. at first i was just accepting it without actually knowing why a higher resistance would equal more power, but know i can understand why. is there a resistor between 10k and 22k that i can test out? isn't there like an 18k or something like that?

 

I know you don't have gauges yet joe. My question is how much resistance is safe keeping EGT's in mind? I know when I did the 10K mine went up and when I pulled I had to slow down to let her cool.

 

You can go to Radio Shack and order specific ones or you can get say a10 and a 4 then hook them in series one right after the other(10+4=14),or if you have the potentiometer then add one in series with it on the pcm side then you will always have a minimum of 4k turn dial up to get 14k.

 

my radioshack has 4.7, 10k, and 22k in stock, in the 1\4 and 1\2 watts, if you want more than the 10k then hook a 10 and a 4.7 inline to make 14.7 k ohms, they have no potentiometers that will work other then a 10k but i find that pointless to run. i do however like the resistor inline with a potentiometer, i'd run a 10k resistor on a 10k potentiometer

Neal, i am sure that even a 10k will boost your egt's to an unsafe level under hard load, most chips will do the same but back off the fuel to keep them under control, once i get gauges i'll run a tow test with the different choices, i just picked up some hose and t-fittings today to rig up a boost gauge to check on my 22k mod problem

cuda, the more resistance the higher the oil goes on indefinatly until the pump reaches 4000 psi, once that happens there is a mechanical check valve that opens to dump the pressure off. i dont know how much resistance that will take, my 22k may be triggering that

on another note, i think i will pull the superchip and retry the 22k to see if it runs better, well it probably wont run better but i am hoping to see the flat line disapear, i figure i have 1 of 3 things happening, overboost and defuel, 4000 psi dump in the pump, or the pump cant keep up with the demand, i feel that the 3rd choice is not the cause since i have no light or codes, if the oil dropped out then the light should come on instantly especially with the resistor in there the pcm wont be able to raise the pressure high enough to keep it off. time will tell

 

ok did a little bit of testing on the mod, first of all i got new pictures of the volt readings, nice and clear now, first the 10k at idle first before the mod and then after


now the 22k first before the mod then after, the idle is a little off from the first pic as the signal slightly varies on all trucks, there isnt a constant number at any given rpm

 

as you can see the 10k is good for .2 volts and the 22k is good for about .4-.5 volts
that translates to the 10k boosting your oil pressure by 200psi and the 22k is good for 400 or a little more. i cant see 400 psi causing my lack of power, i still have to pull the superchip and drive it, its also not de-fuel either, i hooked up a boost gauge, my max was in 3rd gear with the 10k in, just before overdrive shift it hit 15-16 psi, my norm throughout the gears hovered at 10-11 psi. i have no cel, no turbo damage, no boost leaks, fresh oil, fresh fuel filter, clean screen, no uppipe leaks, truck runs strong, cant hit high boost.
with the 22k in it only hits 10 before the flatline starts then it drops off fast it cant be a high pressure oil problem since i dont get a light or a code any ideas untill i can get a scan tool

 

pretty sure its a HPOP oil problems since that is your only change that makes it run like that. You must also remember the the Superchip is also demanding more HP oil than a none chipped truck so the demand is already there and you asking for even more. Plus just cause the computer doesn't set a light doesn't mean its not a problem. We see bad IPR orings all the time here with no CEL or codes.

 

anyway i look at it, i dont like it, the potential is there and i cant use it....aarrggghhh!!! a superduty pump is in the works so it may have to go up higher on the "to-do" list, i just cant see the superchip demanding that much, and the 22k is only asking for 400 more psi, i dont know, i will try to rig up a 5000 psi gauge to the head and see what the actual pressure is before it dies. i am also going to pull the chip and try the 22k and see how she likes that

 

http://danuxoman.smugmug.com/gallery/2943027#196138102

Hey guys and gals. I have been talking to c00nhunterjoe about this mod a little on the side and I don't think we agree on this just yet. I wanted to present some of my findings also and either we can maybe figure out what is going on or we can all just be super-confused. I made a drawing of my interpretation of the ICP circuit and I tried to post it but I just got a big red X. Instead I put up a link to the drawing so you can look at it if you want to.
I am in Iraq right now so I have some difficulty putting my hands on the actual parts, but I did get an ICP sensor off of a 6.0 to take some readings. The actual readings that I got confirmed that there are 2 separate resistors in the sensor. One measures approximately 6 Kohms and the other measures 176 Kohms. The 6 Kohms resistor is teh one that is in the reference leg of my drawing and it is a fixed value. It will not change unless it is affected by temperature. The other resistor is the 176 Kohms resistor and it can also be affected by temperature, but it's main function is to change resistance based on pressure that it senses.
Since the 176Kohms resistor can be affected by temperature, hw does the PCM know if the change in resistance is due to pressure change or temperature change? The answer is temperature compensation. That is the reason for the second resistor and the the third wire on this sensor. The two resistors are equally affected by temperature, but only one is affected by the pressure. The PCM is looking at a difference in the resistance values between the two legs. read that again carefully- the PCM is looking at the difference in the resistance values between the two legs.
That is the whole key to how the ICP mod works.
If you increase the resistance in one leg, you increase the difference between the two legs.
If you decrease the value in the other leg, you increase the difference between the two.
Think of it as making one thing heavier or making the other thing lighter- either way you are increasing the diference between the two.
Sitting on the bench the sensor has 176 Kohms on the signal return leg, and 6 Kohms on the reference leg. The difference between those legs is 170 Kohms.
When you add resistance the way that c00nhunterjoe's mod is set up, you are adding a resistor in series to the 176 Kohm resistor that is looking at the fuel pressure. Adding resistors in series to each other will increase the resistance of that circuit, basically you just add the individual resistors together to get the circuit total resistance. Adding the 22K to the 176 K gives you a reading of 198 Kohms on that leg, but you still only have 6 Kohms onthe other leg. The difference is now 198-6=192 Kohms.
The other way that this mod is performed is to put the resistor into the ICP connector between 2 wires. This method creates a LOWER resistance in the reference leg. By adding resistance in parallel you actually DECREASE the overall resistance because the current can split in to two paths now. I can't figure out how to type the formulas in correctly but follow this link if you want to check my math: http://www.sengpielaudio.com/calculator-paralresist.htm
Now on the reference leg if you add a 10K resistor in parallelto the 6K that is already present, you will get a circuit resistance of 3.75K. The effect that this has on the reading seen by the PCM is that it increases the difference seen- 176-3.75 =172.25. Remember that stock is only 170 so the change is not very dramatic. If you want to take this a step further you can add a 5K instead of a 10K. When the 5K is installed in parallel with the reference resistor the circuit resistance is now 2.72 K, so your difference seen is 176-2.72=173.28 Kohms. The most that you could change the resistance value on the reference leg is by 6K ohms, if you just shorted the reference leg to the signal. The problem with doing that is that you would only create a maximum difference of 6K and you would throw a code in the PCM.
The way that c00nhunterjoe is doing this gives him a much greater potential to change the difference in the two resistances. That is why adding the 22K in series like c00nhunterjoe is doing has a more dramatic effect than adding the resistance in parallel.

Now for the voltage part of this- The way that the PCM knows how much resistance is in the sensor is to send electricity out and see how it reacts to the circuit. The PCM sends out a known voltage and a known current into an unknown resistance. The resistance value is calculated by reading how much voltage comes back on the signal return line, and how much voltage comes back on the reference leg. Both the reference leg and the return leg eventually go to ground. If they didn't you would not have a circuit. If you unplug the connector on the ICP and check it with a voltmeter, you should read 5 volts from the signal line to the signal return. this is because there is an open circuit between the 2 wires. you are now looking at the full voltage. The open circuit is an infinite resistance. There is so much resistance that current can not flow. This will cause a code. In the same sense, if you add too much resistance to the return leg, the voltage will be too close to 5 volts as read from the signal to the signal return. This will throw a code.
If you connect a jumper wire from the signal to the signal return, you now will have a short circuit. there will be no voltage reading from the signal to the signal return because they are basically the same piece of wire now, not 2 separate wires anymore. you must have a load (resistance) between the 2 wires or you will not read a voltage.
Now the next thing to realize is that the current that comes out on the signal wire has 2 paths to choose from- it can go through the reference leg, or it can go through the signal return (measurement) leg. Current will always take the path of least resistance. The majority of the current will go through the reference leg, because it will have less resistance. If the resistance in one leg increases, that leg moves closer to being an open circuit, and the voltage in that leg increases AS MEASURED FROM THE SIGNAL TO THAT LEG.
One more law of electricity comes into play which states that the sum of all voltage drops in a circuit is equal to the total source voltage. What this means is that if you have 5 volts on your signal output, and 1 volt on the reference leg, you MUST have 4 volts on the signal return leg. 4+1=5.
Remember that these numbers are not readings that are referenced to ground. They are readings that are in relation to each other on this one small circuit. Any readings or values that I have given here involve the 2 multimeter leads connected to 2 of the 3 wires in the ICP circuit. I realize that the book is talking about reading to a ground point. The book is not talking about modifying this circuit though.
Now that I may have made the longest post in FTE history I will sit back for a while and watch the sparks fly. I am not trying to prove anyone wrong here, the main objective is that we can all know how and why this mod works, because there is no doubt that it does. c00nhunterjoe is doing this mod differently than the other people who are doing this mod. I believe he will get better results with his method.